The present invention relates to a magnetic motion sensor, having a magnet that generates an essentially homogeneous magnetic field with a magnetic-field direction, and having a coupling element which is arranged inside the magnetic field.
Magnetic motion sensors are widely known and used to measure a motion-dependent physical quantity. In this context, the term motion-dependent physical quantity is intended to mean a physical quantity which, unlike a position-dependent physical quantity, depends on the motion per se.
Motion sensors known in the prior art, utilize a stationary magnet and a mobile coupling element. When the coupling element moves perpendicular to the magnetic-field direction, a motion-dependent physical quantity is induced in the coupling element. The induced quantity is measured and output by a sampling element. Magnetic motion sensors of this type are described, for example, in Gevatter: xe2x80x9cHandbuch der Messund Automatisierungstechnikxe2x80x9d [Handbook of measurement and automation technology], Springer-Verlag, 1999, pages 107f and 115. Ferraris sensors are also constructed in this way.
Due to the motion of the coupling element, only contactless sampling of the motion-dependent physical quantity is possible when using the known magnetic motion sensors. Accordingly, these sensors need to be adjusted precisely. For this reason, they are complicated, susceptible to interference and comparatively expensive.
It is an object of the present invention to provide a simply constructed motion sensor which is robust and not susceptible to interference. This object is achieved by utilizing a mobile magnet and a stationary coupling element. The advantage that is realized by this construction is that the sampling element can then be directly connected mechanically to the coupling element and contactless sampling of the coupling element is not necessary. Nevertheless, even contactless sampling of the coupling element is simplified, because the coupling element is stationary and, no shaking, for example, of the coupling element can occur.
The motion of the magnet may be translational or rotational, according to the desired requirements. The motion-dependent physical quantity may be a force or moment, or a current; and further, the motion-dependent physical quantity may be proportional to velocity or acceleration, according to desired requirements.
The structural design of the magnetic motion sensor of the present invention can be made particularly simple by the following measures:
the magnet is designed as a permanent magnet;
the coupling element is designed as a solid body; and
the coupling element is designed as an electrically conductive element.